PROJECT SUMMARY As many as 86% of women will give birth to at least one child, and pregnancy has long-term consequences for women?s metabolic health, including obesity and glucose homeostasis. However, little is understood about modifiable factors in pregnancy that can improve women?s health postnatally. Phthalates are endocrine disrupting chemicals to which almost all women are exposed from personal care products and food contact materials. Recent evidence suggests that phthalate exposure in pregnancy is associated with disrupted gestational weight gain and glucose homeostasis in mothers. However, whether these metabolic disruptions persist postnatally is not currently known. Therefore, we will leverage an ongoing pregnancy cohort study that has already assessed phthalate concentrations in pregnant women to follow these mothers and ask whether prenatal phthalate exposure is associated with disrupted adiposity and metabolism 4-7 years later. Importantly, we will assess cumulative exposure to a complex mixture of phthalates, since pregnant women have concurrent exposure to numerous phthalates. Phthalates can disrupt estrogen biosynthesis, and several studies (including our preliminary work) suggest that phthalate exposures are associated with disrupted estrogen levels in pregnant women. This is concerning in pregnancy because estrogens have numerous critical functions in pregnant women, including implantation, fetal nutrient transport, and parturition. While estrogenic disruption by phthalates in pregnancy could have deleterious consequences for fetal development and pregnancy outcomes, whether these hormonal disruptions persist postnatally to impact maternal health is not known. Estrogen disruption that persists after pregnancy is potentially harmful for women?s life-long health because in non-pregnant women, estrogens regulate maternal metabolic health, including weight, metabolic efficiency, insulin sensitivity, and appetite. Therefore, the current study will also assess whether exposure to a complex mixture of phthalates in pregnancy is associated with disrupted estrogen levels in women postnatally, and whether these prenatal endocrine disruptions that persists postnatally drive maternal metabolic dysregulations.